Author Topic: What should be used to measure liquids accurately?  (Read 670 times)

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hologram

  • Guest
What should be used to measure liquids accurately?
« on: March 27, 2004, 02:21:00 PM »
I'm trying to figure out how pipettes and such work.  Can you get a pipette that has ml amounts on it so you can measure out your liquid?

  When one buys a pipette from somewhere like ebay do you have to also buy something to get them to pull up liquid?  The ones I see in the pictures look like long thin glass tubes and I don't see how you would pull liquid up with them.

Rhodium

  • Guest
Pipettes
« Reply #1 on: March 27, 2004, 03:35:00 PM »
Large pipettes (graduated in milliliters) and their associated

pipet filler bulbs

(http://www.cbu.edu/~mcondren/c214/pipet/3bulbpic.htm)




Pasteur pipettes (usually 2-3 mL) use small rubber bulbs to draw up liquids:



Now you can use the above keywords to conduct a fruitful google search for more information.


biotechdude

  • Guest
pipette use
« Reply #2 on: March 27, 2004, 04:42:00 PM »
Also remember to read the instruction on their proper use.  There are issues and techniques for correct selection, caliberating, fluid uptake, miniscus, fluid release, cleaning etc etc are built into the pipettes and fillers accuracy ratings. 

Or at least make sure u are consistently doing it the wrong way so the nett varience is negligable.

chilly_willy

  • Guest
also..
« Reply #3 on: April 02, 2004, 04:39:00 PM »
Also dont forget our friend the graduated cylinder.  Very cheap..and very accurate for more practical amounts of liquids 10-200+ml.  Their plastic counterparts are actually better than the glass ones as they dont tip over and break or form a meniscus which can throw off precision readings after you have smoked a little of the kind.  Polymethylpentene is the type to get as the plastic is crystal clear..and highly resistant to MOST any chemical you throw at it.


methyl_ethyl

  • Guest
higher accuracy
« Reply #4 on: April 02, 2004, 08:29:00 PM »
And if you are looking for higher accuracy, there are always type A volumetric pipettes.  Rechargeable battery operated, adjustable, pipette aids are also very useful and are often more controllable than the bulbs.







Grouch

  • Guest
Used for?
« Reply #5 on: April 17, 2004, 05:19:00 PM »
What are you going to hypothetically use it for and how accurate do you need it?  Are you looking for something that measures only mL amounts or to the closest mL?

If you just need something that you can set and forget to dispense liquids with pretty good accuracy to the mL over and over again, I found bottle top dispensers very handy. 

http://www.eppendorf.com/en/?jump=http%3A//www.eppendorf.com/script/cat-nav.php%3Fc%3D1%26l%3D25&jumpmenu=8T



Look for the bottle top dispenser, Varispenser® plus/Varispenser for a picture of one.

pooky

  • Guest
Weight
« Reply #6 on: April 20, 2004, 09:14:00 PM »
If you have an accurate scale,that also works.1 ml H20 is 1 gram etc.

FlyBoy

  • Guest
Good ol' days in Chem class
« Reply #7 on: April 26, 2004, 03:40:00 PM »
I remember in chem class the pipettes that we used had a plastic fitting on the top with a wheel that you turn to draw up or push out liquid. If I had  pic it would greatly help out the both of us (*my explaination). Ah the good old days of titration.


methyl_ethyl

  • Guest
Is this the contraption you are speaking of?
« Reply #8 on: May 01, 2004, 07:11:00 PM »
Is this the contraption you are speaking of?  I have many in my lab, however I have never used them once.   ::)   How it would help you in titrative assay's I have no idea..... 




methyl_ethyl

  • Guest
correct me if I am wrong
« Reply #9 on: May 01, 2004, 07:33:00 PM »
You are saying that .1 mL  of water or 100ul of water is equal to 1 gram of water?  First of all that is a very risky statement.  1mL of H2O is supposedly equivalent to 1 gram of water at STP, AFAIK..  I have found that it depends on what you are weighing, that may have a significant effect on the materials weighed.. Whatever, it is all good....  I think that your initial "diagnosis" of the said situation is quite flawed.  No I am not the "typical" hive member.  I think you are wrong, and you should correct your statement.  i could be wrong, as always, and if you find that I am wrong, please back up your statements with pertinant information that will increase hive intellectual output.

love, as always,

m_e


Rhodium

  • Guest
loss of space
« Reply #10 on: May 01, 2004, 09:00:00 PM »
You are saying that .1 mL  of water or 100ul of water is equal to 1 gram of water?

No, he is saying that 1 mL = 1 g. He missed to press his spacebar - the period is part of the first sentence  ;)